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/*
* Copyright (c) 1988 Mark Nudleman
* Copyright (c) 1988, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifndef lint
static char sccsid[] = "@(#)input.c 8.1 (Berkeley) 6/6/93";
#endif /* not lint */
/*
* High level routines dealing with getting lines of input
* from the file being viewed.
*
* When we speak of "lines" here, we mean PRINTABLE lines;
* lines processed with respect to the screen width.
* We use the term "raw line" to refer to lines simply
* delimited by newlines; not processed with respect to screen width.
*/
#include <sys/types.h>
#include <less.h>
extern int squeeze;
extern int sigs;
extern char *line;
off_t ch_tell();
/*
* Get the next line.
* A "current" position is passed and a "new" position is returned.
* The current position is the position of the first character of
* a line. The new position is the position of the first character
* of the NEXT line. The line obtained is the line starting at curr_pos.
*/
off_t
forw_line(curr_pos)
off_t curr_pos;
{
off_t new_pos;
register int c;
if (curr_pos == NULL_POSITION || ch_seek(curr_pos))
return (NULL_POSITION);
c = ch_forw_get();
if (c == EOI)
return (NULL_POSITION);
prewind();
for (;;)
{
if (sigs)
return (NULL_POSITION);
if (c == '\n' || c == EOI)
{
/*
* End of the line.
*/
new_pos = ch_tell();
break;
}
/*
* Append the char to the line and get the next char.
*/
if (pappend(c))
{
/*
* The char won't fit in the line; the line
* is too long to print in the screen width.
* End the line here.
*/
new_pos = ch_tell() - 1;
break;
}
c = ch_forw_get();
}
(void) pappend('\0');
if (squeeze && *line == '\0')
{
/*
* This line is blank.
* Skip down to the last contiguous blank line
* and pretend it is the one which we are returning.
*/
while ((c = ch_forw_get()) == '\n')
if (sigs)
return (NULL_POSITION);
if (c != EOI)
(void) ch_back_get();
new_pos = ch_tell();
}
return (new_pos);
}
/*
* Get the previous line.
* A "current" position is passed and a "new" position is returned.
* The current position is the position of the first character of
* a line. The new position is the position of the first character
* of the PREVIOUS line. The line obtained is the one starting at new_pos.
*/
off_t
back_line(curr_pos)
off_t curr_pos;
{
off_t new_pos, begin_new_pos;
int c;
if (curr_pos == NULL_POSITION || curr_pos <= (off_t)0 ||
ch_seek(curr_pos-1))
return (NULL_POSITION);
if (squeeze)
{
/*
* Find out if the "current" line was blank.
*/
(void) ch_forw_get(); /* Skip the newline */
c = ch_forw_get(); /* First char of "current" line */
(void) ch_back_get(); /* Restore our position */
(void) ch_back_get();
if (c == '\n')
{
/*
* The "current" line was blank.
* Skip over any preceeding blank lines,
* since we skipped them in forw_line().
*/
while ((c = ch_back_get()) == '\n')
if (sigs)
return (NULL_POSITION);
if (c == EOI)
return (NULL_POSITION);
(void) ch_forw_get();
}
}
/*
* Scan backwards until we hit the beginning of the line.
*/
for (;;)
{
if (sigs)
return (NULL_POSITION);
c = ch_back_get();
if (c == '\n')
{
/*
* This is the newline ending the previous line.
* We have hit the beginning of the line.
*/
new_pos = ch_tell() + 1;
break;
}
if (c == EOI)
{
/*
* We have hit the beginning of the file.
* This must be the first line in the file.
* This must, of course, be the beginning of the line.
*/
new_pos = ch_tell();
break;
}
}
/*
* Now scan forwards from the beginning of this line.
* We keep discarding "printable lines" (based on screen width)
* until we reach the curr_pos.
*
* {{ This algorithm is pretty inefficient if the lines
* are much longer than the screen width,
* but I don't know of any better way. }}
*/
if (ch_seek(new_pos))
return (NULL_POSITION);
loop:
begin_new_pos = new_pos;
prewind();
do
{
c = ch_forw_get();
if (c == EOI || sigs)
return (NULL_POSITION);
new_pos++;
if (c == '\n')
break;
if (pappend(c))
{
/*
* Got a full printable line, but we haven't
* reached our curr_pos yet. Discard the line
* and start a new one.
*/
(void) pappend('\0');
(void) ch_back_get();
new_pos--;
goto loop;
}
} while (new_pos < curr_pos);
(void) pappend('\0');
return (begin_new_pos);
}
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